Method for scarfing



Dc. 19, 1944. w SYLVESTER 2,365,308

METHOD FOR S CARFING Filed March 28, 1942 2 15 FIGZ- IN VENTOR.

WALTER 6. SYL VESTER A 7'TOR/Vf Y Patented Dec. 19, 1944 UNITED STATESPATENT OFFICE Air Reduction Company, Incorporated, New

York, N. Y., a corporation of New York Application March 28, 1942,Serial No. 436,551

3 Claims.

This invention relates to deseaming or scarfing, and more especially toa method for removing metal from a work-piece without leaving fins alongthe edges'of the area from which metal is removed.

When fins are left along the edges of a surfaced area there is some ironin the fins and it is this iron that causes the fins to stick to thework-piece. Auxiliary oxygen streams can be used to complete theoxidation of the iron in the material that would form the fins.

It is an object of this invention to provide an improved method forpreventing fin formation by means of auxiliary oxygen jets. Inaccordance with one feature of the invention the auxiliary jets aresmall as compared with the scarfing oxygen stream and are of highvelocity. Such auxiliary jets conserve oxygen and are easily controlledso that they do not scarf grooves of their own with fins along theseextra grooves.

Another object of the invention is to prevent fin formation moreeffectively by directing the auxiliary oxygen streams from divergingoutlet orifices that produce straight parallel-sided jets that penetratethe products of combustion of the main reaction of the scarfing streamwith the metal of the work-piece.

Another object of the invention is to provide for removing surface metalfrom a work-piece without forming fins along the surfaced area. Variousfeatures of the invention relate to the positioning of auxiliary oxygenjets with respect to the scarfing jet and preheating flames; toauxiliary jet orifices that have diverging outlets for projecting moreeffective streams into the main reaction zone; and to the supplying ofoxygen for the auxiliary jets from sources outside of the tip thatdirects the stream of scarfing oxygen against the work-piece. Thislatter feature has the advantage of making the velocity and volume ofthe auxiliary jets independent of the pressure and velocity of theoxygen in the tip from which the scarfing stream is directed against theworkpiece.

Other objects, features and advantages of the invention will appear orbe pointed out as the specification proceeds.

In the accompanying drawing, forming a part hereof:

Fig. l is an end view of a tip for scarfing in accordance with thisinvention.

Fig. 2 is a side view, mostly in section, of the tip shown in Fig. 1.

Fig. 3 is an end view of a modified form of tip for scarfing inaccordance with this invention.

Fig. 4 is a side view, mostly in section, of the tip shown in Fig. 3.

Figs. 5 and 6 are views similar to Figs. 3 and 4, respectively, butillustrating a second modified tip construction.

The tip 9 shown in Figs. 1 and 2 has a central bore I0 and a divergingoutlet orifice II in axial alinement with the central bore Ill. Thescarfing oxygen stream is discharged from the orifice II.

A circle of preheating flame orifices I! that open through the end faceof the tip are supplied with an oxy-fuel gas mixture through passages i3 in the tip. Between the scarflng oxygen orifice II and the preheatingflame orifices l2, there are a number of auxiliary diverging orifices I4. These orifices H are supplied with oxygen through passages 15directly from the central bore ll) of the tip. The passages l5, like theorifice ll, open through an end wall of the central bore Ill.

The diverging orifices H are designed to expand gas from the pressure inthe passages ii to an outlet pressure substantially equal toatmospheric. The auxiliary jets issuing from the diverging orifices l4have high velocity, preferably of the order of 900 feet per second, orgreater, and the fact that they issue from the tip at atmosphericpressure makes the sides of these jets parallel so that the stream ofgas in each of the auxiliary jets does not expand. Such streams have theadvantage of more effectively penetrating the products of combustion ofthe main reaction of the scarfing oxygen of the central jet with themetal of the work-piece.

Although the expression "diverging orifices" is used in thisspecification and in the claims to describe an orifice having a taperedpassage that increases in cross-section toward its outlet end, the axesof the diverging orifices I also diverge. This permits the auxiliaryjets, that issue from the orifices M in a region between the scarflngoxygen jet and the preheating flame jets, to strike the work-piece alongthe edges of the reaction zone of the central scarfing jet. The scarfingjet spreads out when it strikes the work and the area from which metalis removed is therefore wider than the scarfing jet that issues from thetip.

Figs. 3* and 4 show a tip I 9 that has a central bore 20 and a divergingoutlet orifice 2| in axial alinement with the central bore 20. Thescarflng oxygen stream is discharged from the orifice 2| as in the tipof Figs. 1 and 2.

The tip l9 has preheating flame jet orifices 22 that are the same as thepreheating flame orifices I! of Figs. 1 and 2, but not so numerous andmore widely spaced. Between the preheating flame orifices 22 areauxiliary diverging orifices 24 which are preferably formed in inserts25 pressed into recesses in the face of the tip. The oxygen for theauxiliary orifices 22 is supplied from passages 26 that are of largerdiameter than the inlet ends of the diverging orifices 24, but thatextend for only a limited distance within the tip.

There is an opening 21 in the side of the tip through which each of thepassages 28 communicates with-an annular supply chamber 23 thatsurrounds the tip. The chamber 23 is formed by a housing 29 connected tothe tip. Oxygen is supplied to the chamber 23 through pipes or tubingconnections 30 threaded into the wall of the housing 29. Pipes 30comprise a'supply source for the orifices 24 separate from the supplysource for orifice 2|.

The advantage of this construction over that shown in Figs. 1 and 2 isthat the velocity and volume of the auxiliary oxygen jets that areprojected against the workpiece from the orifices 24 are not dependentupon the pressure or velocity of the oxygen in the central bore 20. Thepressure at which oxygen is supplied to the chamber 28 may be differentfrom that at which oxygen is supplied to the central bore of the tip IS.

The axes of the divergin orifices 24 are parallel, their spacing beingabout equal to the width of the area from which metal is removed by theoxygen scarfing jet from the orifice 2 1.

Figs. and 6 show a conventional scarfing tip 32 with a central orifice33 from which the scarfing jet is directed against the work, and acircle of smaller orifices 34 for directing the preheating flamesagainst the work-piece to raise the surface metal to kindlingtemperature for reaction with the scarfing jet.

For preventing the formation of fins, the tip 32 is equipped with pipes33. having diverging orifices 31 at their outlet ends. The pipes 36comprise a supply source for the orifices 31 separate from the supplysource for orifice 33. As in the case of the chamber 28 in Fig. 4, thepipes 36 are supplied with oxygen from some source outside of the tipand the auxiliary orifices 31 positioned with slightly-converging axesbecause the distance between the orifices 31 is somewhat greater thanthe width of the reaction zone along which the fins would be formed, ifthe auxiliary oxygen Jets were not used to complete the oxidation andprevent any of the metal residue from sticking to the surface of thework-piece as a fin.

The tip 32, equipped with the pipes 36, is used with the pipes 36horizontally spaced from one another on opposite sides of the centralscarfing Jet when scarfing a horizontal surface. With the auxiliary .ietpipes 36 in the positions shown in Figs. 5 and 6, the tip 32 is disposedfor scarfing a vertical surface.

with all of the tips shown' in the drawing, the auxiliary oxygenjetspreferably have high velocity and are of a restricted volume so thatthey react with the products of combustion from the scarfing reaction,but do not attack the surface of the work-piece to produce additionalgrooves which might themselves leave fins along their edges.

Several embodiments of the invention have been described, but variousother changes and modifications can be made and some features of theinvention can be used without others.

I claim:

1. The method of removing surface metal from a ferrous metal work-piecewhich comprises directing an oxygen scarfing stream against the surfaceof the work-piece with the metal at ignition temperature, and, whileproducing relative movement of the stream and work-piece, di-

' recting auxiliary, high-velocity streams of oxygen against thework-piece on both sides of the scarfing stream and close to the sidesof the scarfing stream, said auxiliary high-velocity streams of oxygenbeing substantially smaller than the oxygen scarfing stream anddelivered at substantially atmospheric pressure from orifices whichindividually diverge outwardly so that they will not scarf thework-piece.

2. The method of removing surface metal from a ferrous metal work-piecewhich comprise directing an oxygen scarfing stream against the surfaceof the work-piece with the metal at ignition temperature, and, whileproducing relative movement of the stream and work-piece, directingauxiliary high velocity streams of oxygen against the work-piece on bothsides of the scarfing stream and close to the sides of the scarfingstream, said auxiliary high velocity streams of oxygen beingsubstantiall smaller than the oxygen scarfing stream and delivered atsubstantially atmospheric pressure from orifices which diverge outwardlyfrom one another and which individually diverge outwardly so that theywill not scarf the work-piece.

3. The method of removing surface metal from a work piece as set forthin claim 1 in which the auxiliary oxygen is delivered at a velocity andin a volume independent of the velocity and pressure of the oxygen ofthe scarfing-oxygen stream.

WALTER G. SYLVESTER.

